Not 5%, but Catered To also charges some extra fees on top of the rental rate and villa tax. The contract we signed with them in June stated that we we had to pay them a $50 greeter fee and a $50 late arrival fee (even though we arrived in the afternoon--they told us that they charge the late arrival fee if the property rents for a discount). They also charge a $50 security deposit waiver in lieu of your having to write a check for $1K or whatever. I didn't mind the waiver fee at all but thought the other two charges were kind of weird.
It's like looking in your soup and finding a whole different alphabet.
Caribbean Villas is the largest management firm to charge a 5% fee but there are others. I have run across at least one. I do not remember for sure the company so I will not guess here. I never saw mention of a fee until I received an email stating that the 5% fee was being waived in an attempt to pick up business during the current slow season.
It always seems that Caribbean Villas' villas go for less, so the 5% just sort of evens them out to what other villas rent for. I wouldn't let the 5% stop me, I just add it into the cost of the villa to get the "real" price.